The present invention relates to intraocular lenses. In a first aspect, the invention more particularly relates to an intraocular lens (“IOL”) having a visually observable inversion marker formed on a peripheral section of the optic. The visually observable inversion marker may be seen through an appropriate ophthalmic viewing instrument such as a slit lamp or a binocular microscope during surgery, for example, to aid a surgeon or other practitioner in confirming proper orientation of the IOL within a patient's eye. In a second aspect, the invention provides an IOL having a plunger engagement segment formed on the optic peripheral edge. The plunger engagement segment is configured to inhibit off-axis movement of the IOL relative to a plunger tip when engaged therewith and advanced to inject the IOL into an eye.
IOLs are well known and are used for implanting into an eye to replace the eye's extracted natural lens in a common surgical procedure known as cataract surgery. There are many different types of IOLs available and the surgeon chooses the IOL according to one or more factors including, for example, the physiology and refractive needs of the patient's eye. IOLs are configured with an optic and one or more haptics extending from the optic which act as anchoring elements to properly position the IOL within the eye. The IOL is implanted in the eye with the optic aligned along the eye's visual axis. The IOL may be implanted in a variety of locations within the eye, but typically is positioned within the capsular bag from which the natural lens has been extracted.
The IOL optic typically has a circular peripheral edge with opposite anterior and posterior surfaces. When implanted into an eye, the anterior surface faces toward the pupil and the posterior surface faces toward the retina at the back of the eye. Unless the anterior and posterior surfaces are of the same optical configuration (e.g., symmetrically biconvex), it is important to ensure the anterior surface faces toward the pupil when the IOL is implanted in the eye. For some IOL designs, and in particular IOL designs bilaterally symmetrically disposed about an axis extending perpendicularly through the lens' optical axis, it may be difficult to visually ascertain which surface is the anterior surface and which is the posterior surface. Visually observable inversion markers have thus been provided in prior art IOLs to aid the surgeon in identifying the anterior from the posterior surface of the IOL prior to implantation. For example, as seen in FIG. 1, a prior art IOL 10 is provided having an optic 12 and four haptics 14a-d with a visually observable inversion marker in the form of protrusions 16a,b formed on the haptics 14a and 14c, respectively. Absent protrusions 16a,b, IOL 10 is bilaterally symmetrical about axis X-X extending perpendicularly through optical axis OA and would therefore appear substantially the same when viewed from either the posterior or anterior facing surfaces thereof. Although not shown, instructions would be provided with the IOL 10 instructing the surgeon that the anterior surface is identified when the haptics having the protrusions have their respective lobes 14a′, 14c′ extending in a clockwise direction. As such, prior to implantation and upon viewing the haptics, the surgeon may readily distinguish between the anterior and posterior surfaces. However, once the IOL 10 has been implanted in an eye, surrounding structures of the eye, such as iris 18, may obstruct viewing the haptics 14a-d since the haptics are located posteriorly of iris 18. As such, it is difficult, if not impossible, for a surgeon to confirm whether or not the IOL 10 has been implanted with the anterior surface thereof facing the pupil as required. If the IOL has been inverted with the anterior surface thereof facing the retina rather than the pupil, the IOL will not function properly and must be removed and replaced. There therefore remains a need for an IOL having a visually observable inversion marker which is visually observable to the surgeon after the IOL has been implanted into an eye.
An IOL is implanted in an eye with the aid of an implantation tool such as an IOL injector having a main body portion with a lumen and a plunger telescoping within the lumen. The IOL is placed inside the lumen and the injector tip is inserted into an incision made in the eye. The plunger is then advanced with the plunger tip engaging and pushing the IOL out of the injector and into the eye. The plunger tip may be bifurcated with spaced prongs forming a slot to capture the IOL optic peripheral edge therebetween. Since the IOL optic periphery is typically circular, the plunger tip may unintentionally slip and/or move in an off-axis manner during IOL delivery, particularly once the IOL and plunger tip have exited the lumen. There therefore remains a need for an IOL having a plunger engagement segment which inhibits off-axis movement of the plunger tip relative to the IOL.